1. Field of the Invention
This invention is generally related to soft and flexible plastic tubes having a relatively small diameter of less than 20 mm and thin wall thickness of less than 2.0 mm; said tubes will be deposited as an oil or air supplying passage in vehicles or various types of machines and equipments, and more particularly, this invention relates to an onetouch connecting joint.
2. Description of the Prior Art
Various types of conventional onetouch connecting joints have been developed and disclosed. The majority of them is constructed with a resilient supporting material, such as rubber, which is installed inside the joining main body, and a pawl wall is projected on a portion of the internal peripheral surface. With this structure, the pawl wall portion will be expanded by engaging the plastic tubes externally to said supporting material, so that the pawl wall portion will be forced to be inserted into the outer peripheral surface of the tube to make a firm connection.
However, with the aforementioned conventional methods, since the connection is achieved by simply inserting the soft and resilient plastic tubes into the pawl wall, the insertion on the pawl wall portion could be unnecessarily extended due to the facts that (i) the plastic tubes will be thinned due to an expansion along the tensile direction when an external force is applied to pull them out or (ii) the tubes will be expanded if a high flow pressure is applied on their internal surfaces. These facts will adversely affect the tubes to produce local cracks or fracture thereon due to deterioration of connecting force. This will result in unstable supporting force on the supporting portion and connecting activity as well.